The present invention relates to a control system for an in-cylinder injection type engine and, more particularly, a control system for an in-cylinder injection type engine in which fuel injection and ignition are performed in the compression stroke.
For example, Japanese Patent Application Laid-Open No.11-30177 proposes a method of controlling fuel injection and ignition of an in-cylinder injection type engine in which the fuel injection timing in the compression stroke is modified corresponding to an ignition timing modification amount in order to prevent deterioration of combustion when ignition timing operation is performed for torque operation during stratified burning.
However, the patent does not proposes any detailed modification method (means) in this engine control system in regard to the method of modifying ignition timing corresponding to an ignition timing modification.
An object of the present invention is to propose a detailed control means which is capable of controlling fuel injection timing control in order to maintain a good combustion condition when the injection timing is changed in an in-cylinder injection type engine in which fuel injection and ignition are performed during the compression stroke.
The present invention realizes a control system for an in-cylinder injection type engine comprising a means for injecting fuel into a cylinder of the engine in a compression stroke; a means for igniting the fuel in the compression stroke; a means for determining fuel injection timing and ignition timing from conditions of a rotating speed and a load of the engine; a means for modifying ignition timing from conditions other than the conditions of the rotating speed and the load of the engine; and a means for modifying fuel injection timing, wherein the means for modifying fuel injection timing modifies the fuel injection timing corresponding to the rotating speed of the engine so as to adapt to change of behavior inside a combustion chamber caused by the modification of the ignition timing.
In more detail, the modified value of fuel injection timing is calculated based on the modified value of ignition timing and the rotating speed of the engine.
Further, the modified value of fuel injection timing is calculated based on the modified value of ignition timing and the rotating speed of the engine and a fuel supply pressure.
Further, the means for modifying ignition timing has an allowable limit value for an amount to be changed.
Furthermore, the means for modifying fuel injection timing has an allowable limit value for an amount to be changed.